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The molecular foundations of epidermal cell wall mechanics are critical for understanding structure-function relationships of primary cell walls in plants and facilitating the design of bioinspired materials. To uncover the molecular mechanisms regulating the high extensibility and strength of the cell wall, the onion epidermal wall is stretched uniaxially to various strains and cell wall structures from mesoscale to atomic scale are characterized. Upon longitudinal stretching to high strain, epidermal walls contract in the transverse direction, resulting in a reduced area. Atomic force microscopy shows that cellulose microfibrils exhibit orientation-dependent rearrangements at high strains: longitudinal microfibrils are straightened out and become highly ordered, while transverse microfibrils curve and kink. Small-angle X-ray scattering detects a 7.4 nm spacing aligned along the stretch direction at high strain, which is attributed to distances between individual cellulose microfibrils. Furthermore, wide-angle X-ray scattering reveals a widening of (004) lattice spacing and contraction of (200) lattice spacing in longitudinally aligned cellulose microfibrils at high strain, which implies longitudinal stretching of the cellulose crystal. These findings provide molecular insights into the ability of the wall to bear additional load after yielding: the aggregation of longitudinal microfibrils impedes sliding and enables further stretching of the cellulose to bear increased loads.

The plastic deformation of the microfibrils governs the formation and development of orientation, crystallization, and structural defects in polyacrylonitrile (PAN) fibers due to the flow‐fiber coupling effect during stretching process. In this study, we investigated the morphological changes of microfibrils in PAN fibers during wet‐fiber stretching using ultrathin section technology and electron microscopy observation. Their plastic deformation mechanism was also revealed. An interconnected network was formed and separated by the pore/voids during coagulation process. Stretching forces facilitated the plastic deformation of microfibrils, resulted in their elongation and orientation. Moreover, the inter‐fibril distance reduced and pore/void shape and dimensions were changed. The distinct response of microfibril elements under stretching force resulted in skin‐core structures within the fiber. Tensile strength increased from 27 to 382 MPa, while elongation at break decreased from 225% to 28%. Aligned microfibrils exhibited high tensile strength, whereas unoriented microfibrillar networks showed relatively high elongation properties. Additionally, we proposed a relationship between microfibril morphology changes and fiber mechanical properties. [ABSTRACT FROM AUTHOR]

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Background: The Diplolepideae are the larger group within the Arthrodontae mosses, characterized by peristomes formed from residual cell walls. It is now understood that these peristomes exhibit diverse hygroscopic movements, playing a crucial role in spore release. However, the exact mechanism behind this movement remains unclear, lacking direct evidence. This study investigated the microscopic and submicroscopic structures of the peristomes in three Diplolepideae species: Hypopterygium fauriei (Besch.), Pylaisia levieri (Müll. Hal.) Arikawa and Regmatodon declinatus (Hook.) Brid. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to reveal the differences in their hygroscopic movement mechanisms. Results: The three species exhibited distinct responses upon wetting: H. fauriei's exostome closed inwards, P. levieri' opened outwards, and R. declinatus' elongated significantly. These differences are attributed to the varying microfibril deposition in the exostome layers. Uniform deposition in the inner layer and minimal deposition in the outer layer enabled exostome opening upon wetting and closing when dry. Our findings suggest that the diastole and contraction of fine microfibrils in the exostome plates and ridges are the key drivers of hygroscopic movement. Conclusions: This study provides further evidence at both the structural and submicroscopic levels, contributing to the unraveling of the hygroscopic movement mechanism in Diplolepideae peristomes. This enhanced understanding sheds light on the relationship between peristome structure and function. [ABSTRACT FROM AUTHOR]

Compared with woody fibers, natural non-wood fibers also propose some advantages including more porous, fineness, low density, cheapness, and biodegradability. Without a doubt, the majority of the advancement in cellulose-based materials during the past few years has been the separation of microfibrils from plant sources. Among the agro-residual bast fibers, Helianthus annuus (sunflower) and Saccharum officinarum (sugarcane) are one of the most perceptible fiber crops with superior cellulosic substance. Decortication is the method followed to extract the fiber from the harvested plant stem. The extracted fiber from the plant stem was materialized and investigated after its surface modification by delignification through the kraft pulping process. The inorganic substances were removed from the cellulose fiber to reduce its toughness and to improve its soft, flexible, and liquid absorbency properties. The raw fiber and pulped microfibrils were analyzed under a scanning electron microscope (SEM) which finds the difference in their morphological structure. As beating and grinding of the fiber pulp for wet-laid nonwoven sheet formation were done and a free swell test for pulp was assessed for the absorbency property, it pertains good result ensemble for hygiene products such as cotton and wood pulp. [ABSTRACT FROM AUTHOR]

Abstract Background The Diplolepideae are the larger group within the Arthrodontae mosses, characterized by peristomes formed from residual cell walls. It is now understood that these peristomes exhibit diverse hygroscopic movements, playing a crucial role in spore release. However, the exact mechanism behind this movement remains unclear, lacking direct evidence. This study investigated the microscopic and submicroscopic structures of the peristomes in three Diplolepideae species: Hypopterygium fauriei (Besch.), Pylaisia levieri (Müll. Hal.) Arikawa and Regmatodon declinatus (Hook.) Brid. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to reveal the differences in their hygroscopic movement mechanisms. Results The three species exhibited distinct responses upon wetting: H. fauriei’s exostome closed inwards, P. levieri’ opened outwards, and R. declinatus’ elongated significantly. These differences are attributed to the varying microfibril deposition in the exostome layers. Uniform deposition in the inner layer and minimal deposition in the outer layer enabled exostome opening upon wetting and closing when dry. Our findings suggest that the diastole and contraction of fine microfibrils in the exostome plates and ridges are the key drivers of hygroscopic movement. Conclusions This study provides further evidence at both the structural and submicroscopic levels, contributing to the unraveling of the hygroscopic movement mechanism in Diplolepideae peristomes. This enhanced understanding sheds light on the relationship between peristome structure and function.

Straw and chitosan are underutilized raw materials, which could make a significant contribution to sustainable development. Herein, a novel chitosan-based hydrogel incorporating rice straw cellulose micro-fibrils (SCMF) was prepared to effectively remove Cu(II). FTIR and SEM showed that straw cellulose-g-poly (acrylic acid)/chitosan-g-poly (acrylic acid) interpenetrating polymer networks were prepared and the hydrogel SCCH had a 3D porous structure after cross-linking with AA. The swelling properties of SCCH were studied and compared in various pH solution. The results indicated that SCCH replayed pH responsibility, which had the largest and smallest swelling capacity at pH9.18 and pH4.00 respectively. The pseudo-second-order kinetic model can be effectively used to evaluate swelling kinetics of hydrogels. The effects of contact time and initial concentration on Cu(II) ion removal were investigated. The equilibrium adsorption capacity (Qe) was 209.2 mg/g and the obtained results indicated that the adsorption kinetics conformed to the pseudo-second-order. Chemical adsorption combined with porous physical adsorption endowed SCCH excellent swelling and adsorption properties. Tensile, compression, bending and twisting test convinced that SCMF played a significant role on the improvement of mechanical strength. This novel 3D porous chitosan-based hydrogel was identified to be a promising sorbent with advantages of excellent sorption and mechanical properties. [ABSTRACT FROM AUTHOR]

The transient dimensional changes during hygro-expansion and hydro-expansion of freely and restrained dried, softwood and hardwood sheets and fibers is monitored, to unravel the governing micro-mechanisms occurring during gradual water saturation. The response of individual fibers is measured using a full-field global digital height correlation method, which has been extended to monitor the transient hydro-expansion of fibers from dry to fully saturated. The hygro- and hydro-expansion is larger for freely versus restrained dried and softwood versus hardwood handsheets. The transient sheet-scale hydro-expansion reveals a sudden strain and moisture content step. It is postulated that the driving mechanism is the moisture-induced softening of the so-called "dislocated regions" in the fiber's cellulose micro-fibrils, unlocking further fiber swelling. The strain step is negligible for restrained dried handsheets, which is attributed to the "dislocated cellulose regions" being locked in their stretched configuration during restrained drying, which is supported by the single fiber hydro-expansion measurements. Finally, an inter-fiber bond model is exploited and adapted to predict the sheet-scale hygro-expansion from the fiber level characteristics. The model correctly predicts the qualitative differences between freely versus restrained dried and softwood versus hardwood handsheets, yet, its simplified geometry does not allow for more quantitative predictions of the sheet-scale hydro-expansion. [ABSTRACT FROM AUTHOR]

Polypropylene (PP), as one of the three universal plastics, has been widely used in fields such as medical, automotive, and packaging, etc. The article reviewed the research progress of in-situ microfibrillar technology in PP foaming material, conductive material, and reinforcing and toughing PP in recent years. The results showed that by forming in-situ microfibrils in PP, the melt strength of PP can be improved, the merging of bubbles during the foaming process was reduced, the size of bubbles decreased and the density of bubbles increased, the foaming performance of PP was improved. By forming a conductive microfibrillar network structure in PP, the percolation threshold of PP composites can be effectively reduced. The in-situ formation of microfibrils can significantly improve the crystallization ability of PP, and some polymer microfibrils can induce the formation of shish kebab structure in PP, achieving reinforcement and toughening of PP, meawhile, under the synergistic effect of compatibilizers, its reinforcement and toughening effect on PP was more obvious. [ABSTRACT FROM AUTHOR]

Background: Microbial expansins (EXLXs) are non-lytic proteins homologous to plant expansins involved in plant cell wall formation. Due to their non-lytic cell wall loosening properties and potential to disaggregate cellulosic structures, there is considerable interest in exploring the ability of microbial expansins (EXLX) to assist the processing of cellulosic biomass for broader biotechnological applications. Herein, EXLXs with different modular structure and from diverse phylogenetic origin were compared in terms of ability to bind cellulosic, xylosic, and chitinous substrates, to structurally modify cellulosic fibrils, and to boost enzymatic deconstruction of hardwood pulp. Results: Five heterogeneously produced EXLXs (Clavibacter michiganensis; CmiEXLX2, Dickeya aquatica; DaqEXLX1, Xanthomonas sacchari; XsaEXLX1, Nothophytophthora sp.; NspEXLX1 and Phytophthora cactorum; PcaEXLX1) were shown to bind xylan and hardwood pulp at pH 5.5 and CmiEXLX2 (harboring a family-2 carbohydrate-binding module) also bound well to crystalline cellulose. Small-angle X-ray scattering revealed a 20–25% increase in interfibrillar distance between neighboring cellulose microfibrils following treatment with CmiEXLX2, DaqEXLX1, or NspEXLX1. Correspondingly, combining xylanase with CmiEXLX2 and DaqEXLX1 increased product yield from hardwood pulp by ~ 25%, while supplementing the TrAA9A LPMO from Trichoderma reesei with CmiEXLX2, DaqEXLX1, and NspEXLX1 increased total product yield by over 35%. Conclusion: This direct comparison of diverse EXLXs revealed consistent impacts on interfibrillar spacing of cellulose microfibers and performance of carbohydrate-active enzymes predicted to act on fiber surfaces. These findings uncover new possibilities to employ EXLXs in the creation of value-added materials from cellulosic biomass. [ABSTRACT FROM AUTHOR]

Poly(butylene adipate-co-terephthalate) (PBAT) is one of the most suitable aliphatic–aromatic co-polyesters to replace traditional plastics due to its excellent properties and biodegradability. However, the relatively low mechanical properties limit its large-scale application. Nanocellulose has been attempted to be chemically modified and used to enhance PBAT, but few significant results have been achieved. In this study, three octadecylamine-modified carboxyethyl cellulose microfibrils (OC-CMFs) with different degrees of substitution (DS) were successfully prepared and used to enhance PBAT. The microstructure, chemical structure, hydrophobicity, and thermal stability of the prepared OC-CMFs, as well as the mechanical properties, microstructure, and thermal properties of the OC-CMFs/PBAT composites were characterized. The results show that OC-CMFs have high hydrophobicity, with a water contact angle of up to 132.2°, making them highly dispersed and compatible in the PBAT matrix. When 0.5 wt% OC-CMF with a DS of 0.22 was added, the tensile strength of PBAT increased by 47.8%, while the elongation at break significantly increased by 49.0%. The significant improvement in the PBAT's mechanical properties will help expand its application range and further promote its substitution for non-biodegradable plastics. [ABSTRACT FROM AUTHOR]

In situ microfibrillar poly(lactic acid) (PLA)/polyolefin elastomer (POE) composites (MFCs) with and without compatibilizer POE‐g‐GMA were prepared using a multistage stretching equipment. The results showed that the distribution of PLA inside the POE matrix for the MFCs without compatibilizer was in the form of microfibrils, and most of the PLA microfibrils were well‐oriented and arranged in the matrix. Further, the high PLA content was more likely to form longer PLA microfibrils in MFCs. With the increase in the amount of POE‐g‐GMA for (PLA/POE, 20/80) system, the length of PLA microfibrils significantly decreased, whereas the average diameter increased. The addition of 2 wt% POE‐g‐GMA increased the tensile strength and elongation at the break of POE‐20‐2 by 52.7% and 53.5%, respectively, and the crystallization temperature increased by about 4°C. [ABSTRACT FROM AUTHOR]

Stalk lodging contributes to significant crop yield losses. Therefore, understanding the biomechanical strength and structural rigidity of grain stalks can contribute to improving stalk lodging resistance in crops. From the structural constituents of the stalk, the rind provides the principal structure, supporting cells against tension and bending loads. In this work, the biomechanical and viscoelastic behavior of the rind from the internodes of two sweet sorghum varieties (Della and REDforGREEN (RG)), grown in two different growing seasons, were evaluated by three-point micro-bending tests using a dynamic mechanical analyzer (DMA). In addition, the chemical composition of rinds and the microfibril angle (MFA) of the cell wall were determined using XRD. The results revealed that the biomechanical behavior of Della varieties was stiffer and more resistant to loads than that of RG varieties. Two features of the rind biomechanical properties, flexural modulus (FM) and flexural strength (FS), showed a significant reduction for RG. Particularly, a reduction in FS of 16–37% and in FM of 22–41% were detected for RG1. Changes in the stalks' rind biomechanical properties were attributed to cell wall components. Total lignin and glucan/cellulose contents were positively correlated with the FM and FS of the rind. Subsequently, an increase in the two cell wall components drove an increase in stiffness. Furthermore, the MFA of the rind was also found to influence the rind strength. [ABSTRACT FROM AUTHOR]

Annulus Fibrosus's (AF) multi-directional load-bearing ability manifests from Nature's design wherein type I collagen (COL-I) dominates outer AF and type II collagen (COL-II) dominates inner AF with increase in proteoglycan and water concentration. This indicates a synergistic chemo-mechanical interplay among constituents, contributing towards AF's load-bearing nature. Present work investigates the interplay among COL-I, COL-II and water, and their role in AF collagen fibril nanomechanics using molecular dynamics simulations. Consequently, atomistic models of collagen microfibrils are constructed for four lamellar regions from outer to inner AF, by increasing COL-II and water concentration from 0% to 75%, and 65% to 75%. Results show an increase in local hydration around COL-II component and increase in intermolecular separation (21 Å to 23 Å), with increase in COL-II and water concentration towards inner AF. A combined increase in local hydration and intermolecular separation enhances intermolecular sliding – contributing to a reduction in tensile modulus from 2.1 to 1.6 GPa. Reduction in microfibril tensile modulus towards inner AF contributes to reduction in tensile modulus of AF lamellae towards inner AF, as reported in literature. Furthermore, increase in COL-II and water concentration shifts compressive behaviour from buckling to non-buckling dominant – enhancing collagen fibrils' mechanical stability towards inner AF. [ABSTRACT FROM AUTHOR]

Dysregulation of the extracellular matrix (ECM) occurs widely across cardiovascular pathologies. Recent work has revealed important roles for the «a disintegrin-like and metalloprotease domain with thrombospondin-type 1 motifs like" (ADAMTSL) family of secreted glycoproteins in cardiovascular tissues during development and disease. Key insights in this regard have come from naturally occurring gene mutations in humans and animals that result in severe diseases with cardiovascular manifestations or aortopathies. Expression of ADAMTSL genes is greatly increased in the myocardium during heart failure. Genetically modified mice recapitulate phenotypes of patients with ADAMTSL mutations and demonstrate important functions in the ECM. The novel functions thus disclosed are intriguing because, while these proteins are neither structural, nor proteases like the related ADAMTS proteases, they appear to act as regulatory, i.e., matricellular proteins. Evidence from genetic variants, genetically engineered mouse mutants, and in vitro investigations have revealed regulatory functions of ADAMTSLs related to fibrillin microfibrils and growth factor signaling. Interestingly, the ability to regulate transforming growth factor (TGF)β signaling may be a shared characteristic of some ADAMTSLs. TGFβ signaling is important in cardiovascular development, health and disease and a central driver of ECM remodeling and cardiac fibrosis. New strategies to target dysregulated TGFβ signaling are warranted in aortopathies and cardiac fibrosis. With their emerging roles in cardiovascular tissues, the ADAMTSL proteins may provide causative genes, diagnostic biomarkers and novel treatment targets in cardiovascular disease. Here, we discuss the relevance of ADAMTSLs to cardiovascular medicine. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF) was coated with micro-fibrillated cellulose (MFC) using vacuum-assisted deposition in aqueous suspensions at concentrations of 0.1%, 0.2%, and 0.4%. The impact of distribution mesh configurations (DM arrangements) and fabric layer configuration on cellulose deposition was examined. Multiscale CF-MFC-Epoxy composites were created using resin infusion under flexible tooling, forming a 3D network of MFC between CFs that transferred stress and acted as a node at the intersection of 0–90 bundles. The addition of 0.1% MFC suspensions improved flexural properties, using no distribution media enhanced deposition and penetration efficiency, and drying stacked layers of CF fabrics improved load transference between them. This combination of parameters resulted in composites with a 16% increase in flexural modulus and 45% increase in flexural strength. [ABSTRACT FROM AUTHOR]

Kraft pulp is the most common and economically advantageous raw material for making cellulose nanofibers (CNFs). However, it is revealed that high temperatures and pressures during kraft cooking cause the aggregation of cellulose microfibrils, which reduces the nanofibrillation capability of kraft pulp. Herein, we studied the optimum kraft cooking conditions required to obtain uniform CNFs by preventing aggregation. The fibrillation ability was compared with that of undried pulp treated with purification method only. Suspensions of undried pulps were mechanically fibrillated for various durations. The degree of fibrillation was evaluated by sedimentation, morphology, and water retention values. Kraft pulp cooking at a H-factor of approximately 650 for 140 °C, 160 °C and 170 °C resulted in less fibrillation than in the Wise-based pulp, even at low temperatures such as 140 °C. In contrast to expectations, high matrix substances with lignin contents of 30% did not prevent aggregation of the cellulose microfibrils. The production of CNFs requires a pulping technique for extracting cellulose without aggregation. [ABSTRACT FROM AUTHOR]

Dentifrice performance in the removal of dental plaque is influenced by the interactions of dentifrice components with tooth surfaces. This randomized controlled clinical study assessed the effectiveness and safety of a novel fluoride dentifrice formulation that included a micro-fibrillated cellulose network with entangled microcrystalline cellulose and silica particles (ProtegeraTM), and compared this to a positive control fluoride dentifrice (Crest Cavity Protection™). Whole mouth dental plaque levels in 82 healthy adults were measured after the first supervised use, and following a week of twice daily use at home. Overall, the test dentifrice was at least three times and up to four times more effective in whole-mouth plaque reductions, with a 38.6% reduction on first use, a 30.9% reduction at day 7, and a 41.6% reduction from day 1 to day 7, compared to reductions of 12.0%, 9.6% and 11.6%, respectively for the positive control, and up to seven times more effective in lingual plaque reductions, than the reference dentifrice (p < 0.001), with a 27.7% reduction on first use, a 22.3% reduction at day 7, and a 31.0% reduction from day 1 to day 7, compared to reductions of 4.4%, 2.2%, and 4.5%, respectively, for the positive control. No safety issues arose from the use of the test dentifrice. These results indicate that including micro-fibrillated cellulose enhances plaque removal effectiveness, without causing adverse changes to oral soft tissues. [ABSTRACT FROM AUTHOR]

The mechanics of detachment (e.g., a cylindrical fibril separating from a dissimilar substrate) has been treated in the perspectives of contact mechanics and fracture mechanics theory along with numerical simulations, but systematic experimental studies on the adhesion of an individual microfibril is still scarce. In this work, we conducted a detailed experiment on the adhesion tests of individual cylindrical microfibrils, within a large range of varying diameters from 4 to 400 µm, made of three different polyurethanes with moduli among ~1-40 MPa. We confirmed the scaling effect of an individual microfibril, i.e., the adhesion σad of the individual fibril scales with fibrillar diameters D with an exponent of ~ -0.4 to -0.45. As the fibrillar diameter is reduced below 10 µm, the adhesion becomes unchanged and size insensitive. This result is in good agreement with the theoretical predictions. Furthermore, the effects of the Young's modulus and retraction rates during the adhesion tests on the adhesion strength were also investigated. Our experimental work will provide a guide for the optimal design of the micron-scale surfaces with improved adhesion. [ABSTRACT FROM AUTHOR]

Cellulose microfibrils were isolated from coffee parchment through acid hydrolysis, alkaline hydrolysis, and bleaching. Factorial design experiments allowed studying the influence of the chemical precursor concentrations and reaction times on the mass losses. TGA, SEM, XRD, and FT-IR techniques allowed for characterizing the coffee parchment hydrolyzed and bleached. Obtained results suggest that acid hydrolysis breaks down the lignocellulosic compounds from the coffee parchment, and alkaline hydrolysis allows the solubilization of lignin and hemicellulose. Lignocellulosic compound dissolution produces a reduction/disappearance of some vibrational bands. This dissolution enhances the crystalline index and decreases the microfibril's diameter. However, in coffee parchment, the microfibrils are twisted, giving the appearance of fibers with a minor diameter. The design of the experiment results suggests that the main factors during acid and alkaline hydrolysis are the concentration of the chemical precursors. In the bleaching process, a variation in the factors does not significantly influence the response variable. However, for brightness, the precursor concentration affects the cellulose quality. The optimal conditions for cellulose extraction from coffee parchment are 5% (v/v) of HNO3 by 2 h, 3% (m/v) NaOH by 60 min, and a 1:1 mass of NaClO:CH3COOH by 45 min for bleaching. [ABSTRACT FROM AUTHOR]

The present investigation demonstrated that through microwave treatment of natural fiber wastes, cellulose microfibrils with a purity of 86.82% by weight, a crystallinity percentage of 92.5%, lengths from 1 to 15 mm, and diameters between 7 and 12 µm are obtained. These results were obtained with a one-step methodology, where Agave fibers were suspended in ethylene glycol and irradiated for 5 min with a constant power of 200 W and temperature of 250 °C. In-situ analyses (heating rate, pressure, and aspect ratio of the reaction vial) performed during microwave irradiation, as well as the characterization (thermal, chemical, and morphological) of the treated agave fibers, indicated that dielectric heating of the components of the agave fibers (waxes, pectin, hemicellulose, lignin) produces their depolymerization and leaching towards the reaction medium (ethylene glycol) until their defibration is achieved. The reaction kinetics at different temperatures and times showed that the purification of the fibers starts at 12,000 W. However, to finally obtain the microfibrils, it is necessary to apply 69,812 W. This process has the advantage that the fiber does not have to be treated with chemical substances or mechanical processes before the microwave treatment. Moreover, no additives, reducers, or catalysts are used during or after the treatment, which makes it a novel and optimal process to produce highly pure and crystalline cellulose microfibrils for high-value-added applications. [ABSTRACT FROM AUTHOR]

Pushing the limits of synthetic polymers in terms of stiffness and strength, aromatic polyamide fibers–like Kevlar®–are used for demanding applications in the form of fiber assemblies as ropes. The unique mechanical performance of aramid fiber is intimately linked to its hierarchical structure and orientation, induced during the spinning process. Surprisingly, after nearly 60 years of heavy use, very little is known about damage mechanisms and rational explanation of such high resistance. We report an experimental investigation of the fiber damage mechanisms at the single fiber scale (diameter ≅ 10 μm) with the aim to establish a link with the microstructure. Damage mechanisms and crack propagation are observed in situ for the first time and unveil a widespread damage over the entire length of the fiber in the form of a network of transverse and longitudinal cracks. These observations make it possible to draw a novel scenario of fracture that mitigates the small strain failure hypothesis. To shed light on the crucial role of microfibril cooperativity in fracture toughness, a slight twist is applied to the single fiber to promote tortuosity and frictional contacts between microfibrils. Statistical fracture analysis demonstrated the beneficial impact of such torsion on early failure events, since lowest fracture stresses are shifted to higher stresses. [ABSTRACT FROM AUTHOR]

In his more recent work, Henri Chanzy explored the nature of cellulose microfibrils that were biosynthesized in vitro, in the absence of physical confinement, i.e. external constraints due to the presence of a solid cell wall against which the nanofibrils would be deposited. Henri Chanzy and his colleagues found out by electron diffraction that cellulose IVI could be generated in the native cell wall. At the macroscopic scale, cellulose IVI could hardly be distinguished from cellulose Iβ in powder patterns because of the superimposition of the various signals. In the present work, the use of strongly textured flax or wood specimens was explored in order to generate strong longitudinal (or meridional) 00l patterns in a very wide range of the reciprocal space and with a high resolution. In order to do so, a diffractometer was used with a parafocusing geometry and long scans permitted to document the 002 to 0010 diffraction bands with accuracy, including the odd reflections that are normally present when dealing with cellulose IVI or imperfect forms of cellulose I. An omega scan also demonstrated the extreme selectivity of this setup and the very narrow orientation distribution of the sample. Surprisingly, this study showed that both flax fibres and fir wood contained three characteristic reflections that could be readily distinguished from one another and corresponded to characteristic interplanar spacings. A lineshape analysis using the Williamson–Hall approach and the Hosemann theory was performed on the flax sample. The results provide a better insight as to the longitudinal arrangement of cellulose in terms of domain sizes, microstrains or paracrystallinity. The three forms of order, characterized by various interplanar spacings, were present in different amounts in flax and fir, but the exact match of their interplanar spacing reveals some kind of possible universality in the cellulose arrangement. [ABSTRACT FROM AUTHOR]

X-ray scattering methods allow efficient characterization of cellulosic materials, but interpreting their results is challenging. By creating molecular dynamics models of cellulose microfibrils and calculating the scattering from them, we investigated how different properties of the structures affect their scattering intensities. We studied the effects of hemicelluloses and crystal size on small-angle and wide-angle X-ray scattering (SAXS, WAXS). Microfibril models with and without surface-bound hemicelluloses were built based on the chemical composition of spruce secondary cell walls. The effect of fibril size was investigated by comparing the scattering from fibrils with 14 to 40 cellulose chains. The hemicelluloses appeared in the SAXS region as an increase in the fibril radius and as a clear contribution of a shell around the fibril. The hemicelluloses also increased the crystal size as determined from the broadening of the 200 diffraction peak of cellulose I β . The SAXS and WAXS analysis provided consistent estimates for the size of the microfibrils, and their special features and challenges were discussed. In particular, the results of 18-chain microfibrils were consistent with prior experimental results. Carrying out the simulations in wet and dry environments had the most pronounced effect on fibrils with a hemicellulose coating. Twisting of the fibril had very little impact on most properties, except for a minor effect on the WAXS peaks. The results allow for more correct interpretation of experimental scattering results, leading to more accurate descriptions of microfibril structures in natural and processed cellulosic materials. [ABSTRACT FROM AUTHOR]

Physcomitrium patens is a good model system to study the structure and function relationships of cellulose synthase (CESA) proteins since the life cycle of moss is short and genetic modification is relatively easy. Here, we report a microscopic sum frequency generation (SFG) vibrational spectroscopy analysis of P. patens leaves in a never-dried and fully hydrated state. Using imaging-SFG spectroscopy, cellulose microfibril (CMF) organization in the midrib, laminar, and marginal regions of the gametophore leaf were analyzed separately. The azimuth angle dependence of SFG signals showed that CMFs in the thick stereid cell walls in the midrib are highly aligned along the microfibril angle of ~ 30° with respect to the midrib axis. CMFs in the marginal cell walls also are preferentially tilted toward the longitudinal axis of leaf with the characteristic features of secondary cell walls. On the other hand, CMFs in the lamina cell walls have no preferential orientation and their SFG intensity is low, which is consistent with the primary cell wall property. The thick walls and highly aligned CMFs in the midrib and marginal cells of P. patens leaves are consistent with their support function. [ABSTRACT FROM AUTHOR]

Introduction: The use of biocompatible scaffolds combined with the implantation of neural stem cells, is increasingly being investigated to promote the regeneration of damaged neural tissue, for instance, after a Spinal Cord Injury (SCI). In particular, aligned Polylactic Acid (PLA) microfibrils’ scaffolds are capable of supporting cells, promoting their survival and guiding their differentiation in neural lineage to repair the lesion. Despite its biocompatible nature, PLA is an electrically insulating material and thus it could be detrimental for increasingly common scaffolds’ electric functionalization, aimed at accelerating the cellular processes. In this context, the European RISEUP project aims to combine high intense microseconds pulses and DC stimulation with neurogenesis, supported by a PLA microfibrils’ scaffold.Methods: In this paper a numerical study on the effect of microfibrils’ scaffolds on the E-field distribution, in planar interdigitated electrodes, is presented. Realistic microfibrils’ 3D CAD models have been built to carry out a numerical dosimetry study, through Comsol Multiphysics software.Results: Under a voltage of 10 V, microfibrils redistribute the E-field values focalizing the field streamlines in the spaces between the fibers, allowing the field to pass and reach maximum values up to 100 kV/m and values comparable with the bare electrodes’ device (without fibers).Discussion: Globally the median E-field inside the scaffolded electrodes is the 90% of the nominal field, allowing an adequate cells’ exposure.

Summary: During cell division of the giant‐celled green alga, Valonia utricularis, a lenticular cell is newly formed, which grows from disc‐shaped to globular to obovoid. During the early developmental stages of growth, the cell surface shows a remarkable outward protrusion. In the present study, the anisotropy of cell growth, i.e. the difference between cell surface extension in meridional and radial orientation, was investigated by analyzing the movement of the surface markers in a living cell. Growth was isotropic around the cell zenith but of two different kinds of anisotropic growth in other regions; radial extension was dominant in cell periphery and meridional extension in intermediate regions between zenith and periphery. Moreover, local orientation of cellulose microfibrils was observed on the inner surface of the cell wall during different stages of early development in lenticular cell using an atomic force microscope. Cellulose microfibrils showed meridional orientation overall and this phenomenon was most remarkable in the periphery of the cell, suggesting the possibility of cellulose microfibrils promoting radial extension of cells by suppressing meridional extension of cell wall. [ABSTRACT FROM AUTHOR]

The glomerulopathies associated with the deposition of extracellular fibrils in the glomeruli are subdivided into Congo red positive (amyloidosis) and Congo red negative (non-amyloidotic glomerulopathies) based on Congo red staining. The non-amyloidotic glomerulopathies are divided into immunoglobulin-derived and non-immunoglobulin-derived glomerulopathies. The immunoglobulin-derived glomerulopathies: fibrillary glomerulopathy (FGn) and immunotactoid glomerulopathy (ITG) are rare glomerulopathies. The diagnosis of fibrillary-immunotactoid glomerulopathy depends on electron microscopy, which shows the presence of microfibrils in the glomeruli. The microfibrils in FGn are randomly arranged with diameters less than 30 nm. The microfibrils in ITG are larger than 30 nm with a visible lumen (microtubules), focally arranged in parallel bundles. Patients with fibrillary-immunotactoid glomerulopathy present with proteinuria (usually in the nephrotic range), microscopic hematuria, arterial hypertension, and chronic kidney disease that progresses to kidney failure over months to years. Currently, there are no guidelines for the treatment of fibrillary-immunotactoid glomerulopathy, although immunotactoid glomerulopathy could be associated with underlying hematologic disorders with the need for clone-directed therapy. [ABSTRACT FROM AUTHOR]

In situ special-shaped microfibrillar composites, employing polyolefin elastomer (POE) as matrix and poly(lactic acid)/polyamide 6 (PLA/PA6) masterbatch as dispersed phase, were successfully prepared by using multistage stretching extrusion technology. The special-shaped microfibrils liking "gourd skewers" or "trepang" can be readily tuned by changing the weight ratio of PLA to PA6 in the POE/(PLA/PA6) composites. It was found that the morphological evolution of special shaped structure microfibril were mainly ascribed to the phase separation and viscosity difference between PLA and PA6 during stretching extrusion process. Owing to the large specific surface area and the "hang nail" effect of special-shaped microfibrils, the excellent elongation at break(867%) and tensile strength (20.1 MPa) can be achieved for the POE/(PLA/PA6) composites (PLA/PA6 = 12.5/12.5), which were 1.2 and 2 times higher than those of pure POE respectively. Dynamic rheology studies showed that the viscoelasticity of POE/(PLA/PA6) composites can be improved significantly compared to pure POE. This work provided a facile and cost-effective way to fabricate special shaped microfibrillar composites to improved strength and toughness simultaneously. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is an unbranched biopolymer produced by microorganisms and composed of glucopyranose units linked by β-1,4 bonds. This study investigates the adjuvant action of needle-shaped BC microfibrils (BCmFs) in vitro using bovine serum albumin (BSA) as a model antigen. BC produced by the static culture of Komagataibacter xylinus was then microparticled (1–5 μm) by acid hydrolysis and characterized using Dynamic Light Scattering and Scanning Electron Microscopy. Subsequently, Attenuated Total Reflectance-Fourier-Transform Infrared Spectroscopy, cytotoxicity, TNF-α (tumour necrosis factor-alpha) and IL-6 (interleukin-6) cytokine secretion, and cellular uptake of the BCmFs-BSA conjugate on the human monocyte cell line (U937) differentiated into macrophages were performed. The microfibrils were determined to be 1–5 μm in size, needle-shaped, with a zeta potential of − 32 mV. Their conjugation with the model antigen, BSA, was demonstrated by FTIR analysis. In the cytotoxicity assay, BCmFs-BSA in macrophage cells showed high viability (over 70%). Although the highest TNF-α cytokine level (113 pg/ml) was obtained with BCmFs-BSA (Bovine serum albumin) conjugate (500 µg/ml) and was statistically significant (p = 0.0001) compared to the positive control group (BSA-aluminium hydroxide), IL-6 cytokine levels were not statistically different from those in the control group as desired. It has been shown in macrophage-differentiated U937 cells that microbially synthesized BC in the form of needle-shaped microfibrils (BCmFs) has a high cellular uptake capacity and increases the immunogenicity of the antigen. These results demonstrate for the first time that BCmFs have the potential to serve as a vaccine adjuvant. [ABSTRACT FROM AUTHOR]

Fibrillin-1 microfibrils are essential elements of the extracellular matrix serving as a scaffold for the deposition of elastin and endowing connective tissues with tensile strength and elasticity. Mutations in the fibrillin-1 gene (FBN1) are linked to Marfan syndrome (MFS), a systemic connective tissue disorder that, besides other heterogeneous symptoms, usually manifests in life-threatening aortic complications. The aortic involvement may be explained by a dysregulation of microfibrillar function and, conceivably, alterations in the microfibrils' supramolecular structure. Here, we present a nanoscale structural characterization of fibrillin-1 microfibrils isolated from two human aortic samples with different FBN1 gene mutations by using atomic force microscopy, and their comparison with microfibrillar assemblies purified from four non-MFS human aortic samples. Fibrillin-1 microfibrils displayed a characteristic "beads-on-a-string" appearance. The microfibrillar assemblies were investigated for bead geometry (height, length, and width), interbead region height, and periodicity. MFS fibrillin-1 microfibrils had a slightly higher mean bead height, but the bead length and width, as well as the interbead height, were significantly smaller in the MFS group. The mean periodicity varied around 50–52 nm among samples. The data suggest an overall thinner and presumably more frail structure for the MFS fibrillin-1 microfibrils, which may play a role in the development of MFS-related aortic symptomatology. [ABSTRACT FROM AUTHOR]

Indonesia, particularly the island of Java, is dominated by a number of Shorea tree species (Dipterocarpaceae). Trees of the genus have been utilized for various practices, and they play a fundamental role in managing the stability of tropical forests. This study was carried out to understand the relationships between biomass and microfibril angle in Shorea spp. growing in West Java, where Shorea spp., are abundant. A total of 35 young trees belonging to 5 species were studied. The average age of these trees was 9 years, but in general there was a wide variation in tree diameter and total height. On average, biomass was the highest in S. leprosura and the lowest in S. palembanica. The lowest average microfibril angles (MFAs) were found in S. leprosura and S. mecistopteryx. The regression relationship between biomass and diameter was strong with an R2 value of 0.85, while the strength of the relationship between MFA and diameter was weaker (R2 = 0.195). In general, the MFA degree decreased with increased biomass accumulation Shorea species, which affects tree resistance to environmental variables and competitiveness in Indonesian tropical forests. [ABSTRACT FROM AUTHOR]

Cellulose, the most abundant biopolymer on earth, is a versatile, energy rich material found in the cell walls of plants, bacteria, algae, and tunicates. It is well established that cellulose is crystalline, although the orientational order of cellulose crystallites normal to the plane of the cell wall has not been characterized. A preferred orientational alignment of cellulose crystals could be an important determinant of the mechanical properties of the cell wall and of cellulose-cellulose and cellulose-matrix interactions. Here, the crystalline structures of cellulose in primary cell walls of onion (Allium cepa), the model eudicot Arabidopsis (Arabidopsis thaliana), and moss (Physcomitrella patens) were examined through grazing incidence wide angle X-ray scattering (GIWAXS). We find that GIWAXS can decouple diffraction from cellulose and epicuticular wax crystals in cell walls. Pole figures constructed from a combination of GIWAXS and X-ray rocking scans reveal that cellulose crystals have a preferred crystallographic orientation with the (200) and (110)/([Formula: see text]) planes preferentially stacked parallel to the cell wall. This orientational ordering of cellulose crystals, termed texturing in materials science, represents a previously unreported measure of cellulose organization and contradicts the predominant hypothesis of twisting of microfibrils in plant primary cell walls.

Bamboo fiber cell wall structure, including cellulose microfibril morphology, endows fibers with excellent and stable mechanical strength and toughness. Due to the imaging resolution limitations, the ultra-structure of bamboo fiber cell walls remains elusive. Here we characterized the fiber cell wall's inherent structure and the cellulose microfibril's cross-sectional shape from native and delignified inclined samples, and the tangential sections of moso bamboo using atomic force microscopy. The secondary cell wall sublayer was composed of multiple microfibril layers, 20 nm in thickness each. The 18 nm in diameter spherical particles between microfibrils were lignin. The bamboo fiber cell wall's microfibrils were composed of various numbers of individual cellulose elementary fibrils (CEFs), including one, two, three, four, and multiple CEFs (up to 7 CEFs). The microfibrils' dimensions varied from 3.5 to 40 nm. Additionally, branched microfibrils are described for the first time in the bamboo plant. The study provides insight into the nanometer-scale structure of the fiber cell wall in the bamboo plant. [ABSTRACT FROM AUTHOR]

This study aims to understand the mechanical properties of cellulose nanofibers (CNFs), a nano-sized material element of woods or plants. We develop all-atom (AA) molecular dynamics models of cellulose microfibrils (CMFs), which are the smallest constituent of CNFs. The models were designed for the process of structural failure or the degradation of a hierarchical material of multiple CMF fibers, due to shear deformation. It was assumed that two CMFs were arranged in parallel and in close contact, either in a vacuum or in water. The CMF models in water were built by surrounding AA-modeled water molecules with a few nanometers. Shear deformation was applied in the axial direction of the CMF or in the direction parallel to molecular sheets. Shear moduli were measured, and they agree with previous experimental and computational values. The presence of water molecules reduced the elastic modulus, because of the behavior of water molecules at the interface between CMFs as a function of temperature. In the inelastic region, the CMF often broke down inside CMFs in a vacuum condition. However, in water environments, two CMFs tend to slip away from each other at the interface. Water molecules act like a lubricant between multiple CMFs and promote smooth sliding. [ABSTRACT FROM AUTHOR]

Scientists are drawn to the new green composites because they may demonstrate qualities that are comparable to those of composites made of synthetic fibers due to concerns about environmental contamination. In this work, the potential for using the produced green composite in different buckling load-bearing structural applications is explored. The work on composite buckling characteristics is vital because one needs to know the composite's structural stability since buckling leads to structural instability. The buckling properties of composite specimens with epoxy as the matrix and chemically treated cellulose microfibrils as reinforcements are examined numerically in this study when exposed to axial compressive stress. The numerical model is first created based on the finite element method model. Its validity is checked using ANSYS software by contrasting the critical buckling loads determined through research for three samples. The numerical findings acquired using the finite element method are then contrasted with those produced using the regression equation derived from the ANOVA. The utilization of the created green composite in different buckling load-bearing structural applications is investigated in this study. As a result of the green composite's unaltered buckling properties compared to synthetic composites, it has the potential to replace numerous synthetic composites, improving environmental sustainability. [ABSTRACT FROM AUTHOR]

It is now established that crystalline cellulose is held together not just by hydrogen bonding, but also by dispersion forces and by electrostatic attraction modulated by stereoelectronic factors such as the exo-anomeric effect. The surface chains of native cellulose microfibrils differ in C6 conformation from crystalline cellulose and therefore form different hydrogen bonds, both outward and inward. Dispersion and electrostatic forces, influenced by cellulose conformation, also operate at the microfibril surface. The surface conformation depends on whether cellulose interacts with water, with the surfaces of other microfibrils or with non-cellulosic polymers. Cellulose-water binding competes with other binding interactions, so that diverse surface interactions are finely balanced in free energy, difficult to simulate, and dependent on local details of water structuring about which little is known, especially in the presence of dispersed chains of hemicellulosic or pectic polymers. An example is the influence of hydration on the aggregation of microfibrils as measured by neutron scattering, which is large for primary-wall cellulose and small for hardwood microfibrils. There are many consequent uncertainties about the surface interactions of hydrated cellulose microfibrils, for example how pectins associate with cellulose or why cellulose-xylan interfaces resist hydration. Evidence from a range of experimental technologies, alongside simulations, will be needed to resolve these uncertainties. The practical implications are wide-ranging, from the mechanism of plant growth and the mechanical resilience of wood to the development of novel, wood-based building materials. [ABSTRACT FROM AUTHOR]

It is well established that wood cellulose has highly ordered architecture at scales from a few nanometres to several microns in wood cell wall. Its preferred orientation could be in-situ investigated by polarized Raman spectroscopy. However, the technique is currently underused due to the challenges in sample preparation, instrumentation access and availability of prediction models. Here, a novel strategy is proposed to analyse the microfibril orientation without requiring prior knowledge of the fiber alignment. We derive the mathematical dependence between the incident light polarization angle and the intensity of Raman signal. An updated prediction model of microfibril orientation was thus constructed to replace the previous empirical functions. The problems of degradation and burning were addressed by adjusting the laser power and shortening the acquisition time. The orientation direction of cellulose microfibrils can be determined by the polarization-dependent 1096 cm−1 intensity without rotating sample. The strategy was successfully used to study the variations in molecular orientation throughout a cell wall of balsa wood. It was found that the cellulose microfibrils are arranged spirally to form the cell wall. [ABSTRACT FROM AUTHOR]

Biochemical and biophysical factors need consideration when modelling in vivo cellular behaviour using in vitro cell culture systems. One underappreciated factor is the high concentration of macromolecules present in vivo, which is typically not simulated under standard cell culture conditions. This disparity is especially relevant when studying biochemical processes that govern extracellular matrix (ECM) deposition, which may be altered due to dilution of secreted macromolecules by the relatively large volumes of culture medium required for cell maintenance in vitro. Macromolecular crowding (MMC) utilises the addition of inert macromolecules to cell culture medium to mimic such high concentration environments found in vivo. The present study induced MMC using the sucrose polymer Ficoll and examined whether fibrillin-1 deposition by human lung fibroblasts could be augmented. Fibrillin-1 forms extracellular microfibrils, which are versatile scaffolds required for elastic fibre formation, deposition of other ECM proteins and growth factor regulation. Pathogenic variants in the fibrillin-1 gene (FBN1) cause Marfan syndrome, where ECM deposition of fibrillin-1 can be compromised. Using immunocytochemistry, significantly enhanced fibrillin-1 deposition was observed when lung fibroblasts were cultured under MMC conditions. MMC also augmented fibrillin-1 deposition in Marfan syndrome patient-derived skin fibroblasts in a cell line- and likely FBN1 variant-specific manner. The ability of MMC to increase fibrillin-1 deposition suggested potential applications for tissue-engineering approaches, e.g. to generate tendon or vascular tissues, where fibrillin-1 microfibrils and elastic fibres are key determinants of their biomechanical properties. Moreover, it suggested the potency of MMC to better mimic in vivo ECM environments in cell culture studies.

Renewable fermentation feedstock from a freshly cut oil palm frond (OPF) is a promising medium for bacterial cellulose (BC) production. Herein, this study assessed its suitability as a solitary medium for the production of BC using Acetobacter xylinum 0416 in a static culture. The proximate composition and components analysis revealed up to 36.2 g/L of fermentable sugars and vital nutrients were available in OPF juice. Meanwhile, the effect of OPF juice concentration and initial pH arrangement shows that the maximum yield of BC (2.33 g/L) was obtained using 60% v/v of OPF juice concentration at initial pH 3.5 and incubated at 30℃ for 14 days. Besides, pure OPF juice showed a minimum in BC production due to the presence of inhibitory component suspected to be the lignin content. The kinetic study was elucidated for BC produced from OPF juice and compared with coconut water medium. The FT-IR and XRD spectra, and FE-SEM micrograph analysis for the BC showed the typical peaks represent in cellulose with a crystallinity index of 82.4% and threadlike microfibrils structure ranging from 35.6.5 nm to 77.5 nm. Thus, OPF juice is a solely sufficient medium that offers a positive alternative to BC production. [ABSTRACT FROM AUTHOR]

In Situ microfibrillation is an easy and economical processing method, which has drawn wide concern in recent years. In Situ special-shaped microfibrillar composites, which with poly(lactic acid)/polyamide 6 (PA6/PLA) together formed special-shaped microfibrils in polyolefin elastomer (POE) matrix, were successfully prepared by using multistage stretching extrusion technology. Four types of PA6 with different viscosity were utilized to investigate the effect of viscosity ratio of PA6 to PLA on the structure evolution of special-shaped microfibrils and the mechanical properties of POE/(PA6/PLA) composites. The morphological observation showed that the viscosity ratio was closely associated to the size and shape of PA6 and greatly affected the microfibrillar morphology of PLA/PA6. When the viscosity ratio of PA6 to PLA was less than 2.2, the "gourd-skewers-like" structure microfibrils were obtained. When the viscosity ratio of PA6/PLA to 14.2 was further increased, the "trepang" structure microfibrils were dominant. The "gourd skewers" structure microfibrils were favorable to improvement the tensile strength, Young's modulus, and viscoelastic properties of POE/(PA6/PLA) blends compared to the "trepang" structure microfibrils. In addition, the morphology of microfibrils exhibited a negligible effect on the melting and crystallization temperature and crystallization degree of PLA and POE matrix. This work provides a new strategy for designing the in situ special-shaped microfibrillar composites with improved mechanical properties. [ABSTRACT FROM AUTHOR]

In situ microfibrillar ethylene–octene copolymer (POE)/poly(lactic acid) (PLA) composites (MFCs) with different phase morphologies were prepared by controlling the stretching speed and maintaining the weight ratio of POE/PLA of 80/20. Four different stretching speeds were employed to study the effect of PLA microfibrillar morphology on tensile, crystalline, and rheological properties of MFCs. Scanning electron microscopic images revealed that the morphology of PLA phase was strongly influenced by stretching speed. MFCs with highest aspect ratio and smaller diameter of PLA microfibrils were obtained with a stretching speed of 60 rpm. The PLA microfibrils with high aspect ratio had the best reinforcement effect on MFCs. The dynamic rheological properties indicated that the MFCs achieved higher storage modulus and loss modulus at the stretching speed of 60 rpm. [ABSTRACT FROM AUTHOR]

This study introduces the usage of date palm fibers (DPFs) as reinforcement of geopolymer matrices. The DPFs were subjected to alkaline treatment by immersion in alkaline solution (5 M) for 24 h at 40 °C. Because of the subsequent strong alkaline geopolymerization, the natural resin (lignin) was removed and the DPFs with a diameter around 600 µm on average broke down into microfibrils with an average diameter of 50 µm. The resultant microfibrils with a large surface area form a strong fiber-matrix adhesion force, thus leading to improved mechanical performance of the composite. The DPF-reinforced geopolymer composite (DPCs) are studied by examining their ductility, high elongation, and strain hardening with a modulus of 200 MPa. The experimental results indicate better mechanical properties of geopolymer composites when compared to the reference geopolymers. The flexural strength of the DPF-geopolymer composite is 12.5 MPa, more than four times the strength of reference geopolymers. The contribution of this research lies in developing attractive green composites based on DPFs and kaolinite. Reinforcement of the geopolymers with natural, abundant, recyclable, and reusable DPFs not only helps improve the mechanical performance of the composites, it also reduces CO2 emission from burning them. The novelty of this study is that microfibrils are extracted from the DPFs during the alkali geopolymerization reactions. These microfibrils are characterized by high surface areas, and subsequently high adhesion forces with the geopolymer matrix. [ABSTRACT FROM AUTHOR]

• 78% of lignin was extracted from pinewood at 120 °C. • Efficient glucan conversion was achieved after alkaline post-incubation. • SAXS revealed the solvent effect on microfibrils. Cyrene organosolv fractionation effectively extracted 78 % of lignin from recalcitrant softwood biomass pine at a mild temperature of 120 °C. However, the enzymatic conversion of the fractionated cellulose-rich solid did not improve significantly. Alkali post-incubation of the fractionated cellulose fraction notably enhanced the glucan conversion. This phenomenon has also been observed in other organosolv processes, but how this approach transforms pretreated biomass has not yet been comprehensively investigated. In this study, small-angle X-ray scattering (SAXS) was employed to understand the structural changes in biomass during fractionation and post-incubation at the nanometer scale. No lignin aggregation was found on the microfibrils, whereas the distance between the microfibrils increased after pretreatment and decreased after alkaline post-incubation. These results suggests that the Cyrene molecules remained between the microfibrils and were removed by post-incubation. In addition, the pine lignin recovered after pretreatment was characterized by NMR to understand the impact of Cyrene pretreatment on the lignin structure. [ABSTRACT FROM AUTHOR]

Cellulose microfibrils are crucial for many of the remarkable mechanical properties of primary cell walls. Nevertheless, many structural features of cellulose microfibril organization in cell walls are not yet fully described. Microscopy techniques provide direct visualization of cell wall organization, and quantification of some aspects of wall microstructure is possible through image processing. Complementary to microscopy techniques, scattering yields structural information in reciprocal space over large sample areas. Using the onion epidermal wall as a model system, we introduce resonant soft X-ray scattering (RSoXS) to directly quantify the average interfibril spacing. Tuning the X-ray energy to the calcium L-edge enhances the contrast between cellulose and pectin due to the localization of calcium ions to homogalacturonan in the pectin matrix. As a consequence, RSoXS profiles reveal an average center-to-center distance between cellulose microfibrils or microfibril bundles of about 20 nm.

Bacterial cellulose ionogels (BCIGs) represent a new class of material comprising a significant content of entrapped ionic liquid (IL) within a porous network formed from crystalline cellulose microfibrils. BCIGs suggest unique opportunities in separations, optically active materials, solid electrolytes, and drug delivery due to the fact that they can contain as much as 99% of an IL phase by weight, coupled with an inherent flexibility, high optical transparency, and the ability to control ionogel cross-sectional shape and size. To allow for the tailoring of BCIGs for a multitude of applications, it is necessary to better understand the underlying principles of the mesoscopic confinement within these ionogels. Toward this, we present a study of the structural, relaxation, and diffusional properties of the ILs, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpy][Tf2N]), using 1H and 19F NMR T1 relaxation times, rotational correlation times, and diffusion ordered spectroscopy (DOSY) diffusion coefficients, accompanied by molecular dynamics (MD) simulations. We observed that the cation methyl groups in both ILs were primary points of interaction with the cellulose chains and, while the pore size in cellulose is rather large, [emim]+ diffusion was slowed by ∼2-fold, whereas [Tf2N]− diffusion was unencumbered by incorporation in the ionogel. While MD simulations of [bmpy][Tf2N] confinement at the interface showed a diffusion coefficient decrease roughly 3-fold compared to the bulk liquid, DOSY measurements did not reveal any significant changes in diffusion. This suggests that the [bmpy][Tf2N] alkyl chains dominate diffusion through formation of apolar domains. This is in contrast to [emim][Tf2N] where delocalized charge appears to preclude apolar domain formation, allowing interfacial effects to be manifested at a longer range in [emim][Tf2N]. [ABSTRACT FROM AUTHOR]

Many woody eudicot plants form a secondary xylem composed of gelatinous fibers (G-fibers) called "tension wood" (TW) along the upper side of the tilted stem or branch. TW generates a large tensile growth stress in the longitudinal direction, allowing the tilted stem or a branch to develop negative-gravitropism in response to the strong gravitational stimulus. This is because the G-fiber tends to contract in the longitudinal direction as it matures. The matured G-fiber also contracts upon boiling in water (= hygrothermal treatment, i.e., HT-treatment), and moisture desorption (= drying treatment). These contractions occur in the cellulose-rich gelatinous layer (G-layer) as an innermost layer of the G-fiber. It is still an unsolved mystery how the G-layer, which is composed of highly crystallized and longitudinally oriented cellulose microfibrils (CMFs), contracts during maturation, boiling, and drying. In the present study, TW specimen of Konara oak (Quercus serrata L.) was subjected to HT-treatment under different temperature and time conditions, and strain due to treatment was followed. Besides, the mass loss due to HT-treatment was also followed. Obtained results are summarized as follows. (1) Green TW specimen of Konara oak contracted in the longitudinal direction when subjected to the HT-treatment at a treatment temperature higher than 40 °C, which eventually converged to a constant value according to each treatment temperature. Magnitude of the longitudinal HTR-strain in the TW specimen was positively correlated with the treatment temperature in the range from 40 to 120 °C, whereas in the normal wood (NW) specimen, it does not occur explicitly when the temperature is less than 100 °C. (2) Both TW and NW specimens showed mass loss when subjected to the HT-treatment. The mass loss rate increased rapidly by the HT-treatment at 120 °C, while it was only slight below 100 °C. There was no significant difference between the mass loss behavior of TW and NW by the HT-treatment. From analyzing those results, physical behavior of CMF and other non-cellulosic matrix components in the G-layer during the HT-treatment was estimated. The discussion was further developed to associate HT-contraction with microscopic mechanisms of the other two characteristic contractions of the G-fiber, i.e., maturation strain and drying shrinkage. [ABSTRACT FROM AUTHOR]

Cellulose-based handmade paper records a substantial amount of historical data and promotes human civilization. Due to the complexity of its structure and external factors, the deterioration of paper in the restoration of ancient books cannot be completely stopped. Nonetheless, the lack of microstructure analysis of handmade paper limits the understanding of its aging mechanism and storage life-span. Herein, CP/MAS 13C NMR method was used to estimate the cellulose types, crystallinity, average lateral fibril dimension (LFD), and the average lateral fibril aggregate dimension (LFAD), relying on integrated spectral fitting from C1, C4, and C6 regions, respectively. Consequently, cellulose Iβ crystals were predominant in all handmade paper samples. Based on the results of C4 and C6 regions by peak separation method, bast paper (Kaihua paper and Yingchun paper) demonstrated a higher crystallinity than bamboo paper (Yuanshu paper). Additional analysis of the C4 data revealed that bast papers exhibit larger cellulose microfibrils, and their LFDs and LFADs were greater than bamboo papers. Moreover, external stress of Wiley milling reduced the LFAD from the original 9 elementary fibrils to 4 elementary fibrils with unchanged LFDs. [ABSTRACT FROM AUTHOR]